git.ozlabs.org Git - ccan/blob - ccan/io/poll.c

   1 /* Licensed under LGPLv2.1+ - see LICENSE file for details */
   2 #include "io.h"
   3 #include "backend.h"
   4 #include <assert.h>
   5 #include <poll.h>
   6 #include <stdlib.h>
   7 #include <sys/types.h>
   8 #include <sys/socket.h>
   9 #include <limits.h>
  10
  11 static size_t num_fds = 0, max_fds = 0, num_finished = 0, num_waiting = 0;
  12 static struct pollfd *pollfds = NULL;
  13 static struct fd **fds = NULL;
  14 static struct timers timeouts;
  15
  16 static bool add_fd(struct fd *fd, short events)
  17 {
  18         if (num_fds + 1 > max_fds) {
  19                 struct pollfd *newpollfds;
  20                 struct fd **newfds;
  21                 size_t num = max_fds ? max_fds * 2 : 8;
  22
  23                 newpollfds = realloc(pollfds, sizeof(*newpollfds) * num);
  24                 if (!newpollfds)
  25                         return false;
  26                 pollfds = newpollfds;
  27                 newfds = realloc(fds, sizeof(*newfds) * num);
  28                 if (!newfds)
  29                         return false;
  30                 fds = newfds;
  31                 max_fds = num;
  32         }
  33
  34         pollfds[num_fds].fd = fd->fd;
  35         pollfds[num_fds].events = events;
  36         pollfds[num_fds].revents = 0; /* In case we're iterating now */
  37         fds[num_fds] = fd;
  38         fd->backend_info = num_fds;
  39         num_fds++;
  40         if (events)
  41                 num_waiting++;
  42
  43         return true;
  44 }
  45
  46 static void del_fd(struct fd *fd)
  47 {
  48         size_t n = fd->backend_info;
  49
  50         assert(n != -1);
  51         assert(n < num_fds);
  52         if (pollfds[n].events)
  53                 num_waiting--;
  54         if (n != num_fds - 1) {
  55                 /* Move last one over us. */
  56                 pollfds[n] = pollfds[num_fds-1];
  57                 fds[n] = fds[num_fds-1];
  58                 assert(fds[n]->backend_info == num_fds-1);
  59                 fds[n]->backend_info = n;
  60         } else if (num_fds == 1) {
  61                 /* Free everything when no more fds. */
  62                 free(pollfds);
  63                 free(fds);
  64                 pollfds = NULL;
  65                 fds = NULL;
  66                 max_fds = 0;
  67         }
  68         num_fds--;
  69         fd->backend_info = -1;
  70         close(fd->fd);
  71 }
  72
  73 bool add_listener(struct io_listener *l)
  74 {
  75         if (!add_fd(&l->fd, POLLIN))
  76                 return false;
  77         return true;
  78 }
  79
  80 static void adjust_counts(enum io_state state)
  81 {
  82         if (state == IO_FINISHED)
  83                 num_finished++;
  84 }
  85
  86 static void update_pollevents(struct io_conn *conn)
  87 {
  88         struct pollfd *pfd = &pollfds[conn->fd.backend_info];
  89
  90         if (pfd->events)
  91                 num_waiting--;
  92
  93         pfd->events = conn->plan.pollflag;
  94         if (conn->duplex) {
  95                 int mask = conn->duplex->plan.pollflag;
  96                 /* You can't *both* read/write. */
  97                 assert(!mask || pfd->events != mask);
  98                 pfd->events |= mask;
  99         }
 100         if (pfd->events)
 101                 num_waiting++;
 102
 103         adjust_counts(conn->plan.state);
 104 }
 105
 106 bool add_conn(struct io_conn *c)
 107 {
 108         if (!add_fd(&c->fd, c->plan.pollflag))
 109                 return false;
 110         adjust_counts(c->plan.state);
 111         return true;
 112 }
 113
 114 bool add_duplex(struct io_conn *c)
 115 {
 116         c->fd.backend_info = c->duplex->fd.backend_info;
 117         update_pollevents(c);
 118         return true;
 119 }
 120
 121 static void del_conn(struct io_conn *conn)
 122 {
 123         assert(conn->plan.state == IO_FINISHED);
 124         if (conn->finish)
 125                 conn->finish(conn, conn->finish_arg);
 126         if (timeout_active(conn))
 127                 backend_del_timeout(conn);
 128         free(conn->timeout);
 129         if (conn->duplex) {
 130                 /* In case fds[] pointed to the other one. */
 131                 fds[conn->fd.backend_info] = &conn->duplex->fd;
 132                 conn->duplex->duplex = NULL;
 133         } else
 134                 del_fd(&conn->fd);
 135         num_finished--;
 136 }
 137
 138 void del_listener(struct io_listener *l)
 139 {
 140         del_fd(&l->fd);
 141 }
 142
 143 static void backend_set_state(struct io_conn *conn, struct io_plan plan)
 144 {
 145         conn->plan = plan;
 146         update_pollevents(conn);
 147 }
 148
 149 void backend_wakeup(struct io_conn *conn)
 150 {
 151         update_pollevents(conn);
 152 }
 153
 154 static void accept_conn(struct io_listener *l)
 155 {
 156         int fd = accept(l->fd.fd, NULL, NULL);
 157
 158         /* FIXME: What to do here? */
 159         if (fd < 0)
 160                 return;
 161         l->init(fd, l->arg);
 162 }
 163
 164 /* It's OK to miss some, as long as we make progress. */
 165 static void finish_conns(void)
 166 {
 167         unsigned int i;
 168
 169         for (i = 0; !io_loop_return && i < num_fds; i++) {
 170                 struct io_conn *c, *duplex;
 171
 172                 if (!num_finished)
 173                         break;
 174
 175                 if (fds[i]->listener)
 176                         continue;
 177                 c = (void *)fds[i];
 178                 for (duplex = c->duplex; c; c = duplex, duplex = NULL) {
 179                         if (c->plan.state == IO_FINISHED) {
 180                                 del_conn(c);
 181                                 free(c);
 182                                 i--;
 183                         }
 184                 }
 185         }
 186 }
 187
 188 static void ready(struct io_conn *c)
 189 {
 190         backend_set_state(c, do_ready(c));
 191 }
 192
 193 void backend_add_timeout(struct io_conn *conn, struct timespec duration)
 194 {
 195         if (!timeouts.base)
 196                 timers_init(&timeouts, time_now());
 197         timer_add(&timeouts, &conn->timeout->timer,
 198                   time_add(time_now(), duration));
 199         conn->timeout->conn = conn;
 200 }
 201
 202 void backend_del_timeout(struct io_conn *conn)
 203 {
 204         assert(conn->timeout->conn == conn);
 205         timer_del(&timeouts, &conn->timeout->timer);
 206         conn->timeout->conn = NULL;
 207 }
 208
 209 /* This is the main loop. */
 210 void *io_loop(void)
 211 {
 212         void *ret;
 213
 214         while (!io_loop_return) {
 215                 int i, r, timeout = INT_MAX;
 216                 struct timespec now;
 217
 218                 if (timeouts.base) {
 219                         struct timespec first;
 220                         struct list_head expired;
 221                         struct io_timeout *t;
 222
 223                         now = time_now();
 224
 225                         /* Call functions for expired timers. */
 226                         timers_expire(&timeouts, now, &expired);
 227                         while ((t = list_pop(&expired, struct io_timeout, timer.list))) {
 228                                 struct io_conn *conn = t->conn;
 229                                 /* Clear, in case timer re-adds */
 230                                 t->conn = NULL;
 231                                 backend_set_state(conn, t->next(conn, t->next_arg));
 232                         }
 233
 234                         /* Now figure out how long to wait for the next one. */
 235                         if (timer_earliest(&timeouts, &first)) {
 236                                 uint64_t f = time_to_msec(time_sub(first, now));
 237                                 if (f < INT_MAX)
 238                                         timeout = f;
 239                         }
 240                 }
 241
 242                 if (num_finished) {
 243                         finish_conns();
 244                         /* Could have started/finished more. */
 245                         continue;
 246                 }
 247
 248                 if (num_fds == 0)
 249                         break;
 250
 251                 /* You can't tell them all to go to sleep! */
 252                 assert(num_waiting);
 253
 254                 r = poll(pollfds, num_fds, timeout);
 255                 if (r < 0)
 256                         break;
 257
 258                 for (i = 0; i < num_fds && !io_loop_return; i++) {
 259                         struct io_conn *c = (void *)fds[i];
 260                         int events = pollfds[i].revents;
 261
 262                         if (r == 0)
 263                                 break;
 264
 265                         if (fds[i]->listener) {
 266                                 if (events & POLLIN) {
 267                                         accept_conn((void *)c);
 268                                         r--;
 269                                 }
 270                         } else if (events & (POLLIN|POLLOUT)) {
 271                                 r--;
 272                                 if (c->duplex) {
 273                                         int mask = c->duplex->plan.pollflag;
 274                                         if (events & mask) {
 275                                                 ready(c->duplex);
 276                                                 events &= ~mask;
 277                                                 if (!(events&(POLLIN|POLLOUT)))
 278                                                         continue;
 279                                         }
 280                                 }
 281                                 ready(c);
 282                         } else if (events & POLLHUP) {
 283                                 r--;
 284                                 backend_set_state(c, io_close(c, NULL));
 285                                 if (c->duplex)
 286                                         backend_set_state(c->duplex,
 287                                                           io_close(c->duplex,
 288                                                                    NULL));
 289                         }
 290                 }
 291         }
 292
 293         while (num_finished)
 294                 finish_conns();
 295
 296         ret = io_loop_return;
 297         io_loop_return = NULL;
 298         return ret;
 299 }